Mariah Carey
Mariah joined Jenny Craig after giving birth to her twins, Moroccan and Monroe. Through diet and exercise, she has managed to drop 70 pounds and looks absolutely amazing!
Angie Everhart
Angie Everhart turned to Nutrisystem to help her lose 40 pounds after the birth of her baby boy in 2009.
Carrie Underwood
Eating well and exercising regularly helped Carrie drop almost 20 pounds off of her petite frame!
Jennifer Hudson
"It's like a brand-new me," the American Idol singer told Oprah after dropping a whopping 80 pounds with the help of Weight Watchers. "Sometimes I don't even recognize myself."
Kellie Pickler
The country cutie who is known for standing by her friends said she packed on the pounds by sympathy eating with a pregnant pal. She bounced right back into shape by sticking to a healthy diet.
Seth Rogen
The Green Hornet funnyman didn't just laugh off his weight. He used diet and exercise to get fit for the superhero role.
Kirstie Alley
Making it to the Dancing With the Stars finale last year sure helped this Fat Actress shed 100 pounds.
Jordin Sparks
The season six American Idol champ shrunk from a size 14 to a size 8—but a smaller waistline isn't the only thing the "Tattoo" singer is sporting these days.
Jonah Hill
How does the Superbad funnyguy keep the weight off? "Just eating healthy, running and doing push-ups," the slimmed-down actor recently told us.
Star Jones
After reaching over 300 pounds back in 2009, the Celebrity Apprentice star lost half her body weight after turning to gastric bypass surgery to get healthy.
Sara Rue
The Rules of Engagement actress joined team Jenny Craig in December of last year and has since lost 50 pounds.
Nicole Richie
The now mother of two admitted to being overly skinny back in 2006 after her major weight loss, telling Vanity Fair, "I'm not happy with the way I look right now."
Drew Carey
"You can only wear fat clothes, you don't feel good, your sex life gets damaged, you don't have energy for anything," the now 80 pounds thinner Price Is Right host told Parade about living life at his heaviest weight (262 pounds).
Lea Michelle
Let's face it, Glee's Lea Michele always looks great, but sticking to a vegan diet helps the sexy star always look camera-ready!
Kristen Johnston
After a health scare in 2006, the Bride Wars actress lost a shocking 60 pounds, admitting to People, "I was way too thin."
Al Roker
The Today Show cohost dropped over 100 pounds after having gastric bypass surgery in 2002.
Raven Symone
"I thought I looked fabulous before and nobody else did," the now super slender star told People of her body transformation.
Randy Jackson
The slimmed-down American Idol judge wrote Body With Soul, a health book, after loosing over 100 pounds in 2003 with gastric bypass.
Oprah
The TV talk-show titan's weight has gone up and down more times than a yo-yo over the years.
Kelly Osbourne
"The three things I did to really change my diet were: Start eating breakfast, drink water instead of soda, and always have a snack in the evening," says the Fashion Police starlet in Shape magazine. Check her out steaming up the cover with her new bikini bod.
Mandy Moore
Mandy Moore toned up her gorgeous gams by eating healthy, doing Pilates and hiking!
Mo'Nique
From 262 pounds down to 206, the Oscar-winning actress has a much healthier figure today and continues working out at 5:30 a.m. at least five times a week to get down to her goal weight of 180.
Valerie Bertinelli
Hot in Cleveland ? This 51-year-old is looking hot, period!
Janet Jackson
As a famous yo-yo dieter, Janet Jackson seems to have shed the pounds for good this time, thanks to Nutrisystem.